/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * KOML.java
 * Copyright (C) 2004-2012 University of Waikato, Hamilton, New Zealand
 */

package weka.core.xml;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * This class is a helper class for XML serialization using
 * <a href="http://koala.ilog.fr/XML/serialization/" target="_blank">KOML</a> .
 * KOML does not need to be present, since the class-calls are done generically
 * via Reflection.
 * 
 * @author FracPete (fracpete at waikato dot ac dot nz)
 * @version $Revision 1.0$
 */
public class KOML {

    /**
     * indicates whether
     * <a href="http://koala.ilog.fr/XML/serialization/" target="_blank">KOML</a>
     * (Koala Object Markup Language) is present
     */
    protected static boolean m_Present = false;

    /** the extension for KOML files (including '.') */
    public final static String FILE_EXTENSION = ".koml";

    /** check for KOML statically (needs only to be done once) */
    static {
        checkForKOML();
    }

    /**
     * checks whether the KOML is present in the class path
     */
    private static void checkForKOML() {
        try {
            Class.forName("fr.dyade.koala.xml.koml.KOMLSerializer");
            m_Present = true;
        } catch (Exception e) {
            m_Present = false;
        }
    }

    /**
     * returns whether KOML is present or not, i.e. whether the classes are in the
     * classpath or not
     * 
     * @return whether KOML is available
     */
    public static boolean isPresent() {
        return m_Present;
    }

    /**
     * reads the XML-serialized object from the given file
     * 
     * @param filename the file to deserialize the object from
     * @return the deserialized object
     * @throws Exception if something goes wrong while reading from the file
     */
    public static Object read(String filename) throws Exception {
        return read(new FileInputStream(filename));
    }

    /**
     * reads the XML-serialized object from the given file
     * 
     * @param file the file to deserialize the object from
     * @return the deserialized object
     * @throws Exception if something goes wrong while reading from the file
     */
    public static Object read(File file) throws Exception {
        return read(new FileInputStream(file));
    }

    /**
     * reads the XML-serialized object from a stream
     * 
     * @param stream the stream to deserialize the object from
     * @return the deserialized object
     * @throws Exception if something goes wrong while reading from the stream
     */
    public static Object read(InputStream stream) throws Exception {
        Class<?> komlClass;
        Class<?>[] komlClassArgs;
        Object[] komlArgs;
        java.lang.reflect.Constructor<?> constructor;
        Object koml;
        java.lang.reflect.Method methodRead;
        java.lang.reflect.Method methodClose;
        Class<?>[] readArgsClasses;
        Class<?>[] closeArgsClasses;
        Object[] readArgs;
        Object[] closeArgs;
        Object result;

        result = null;

        // get Deserializer
        komlClass = Class.forName("fr.dyade.koala.xml.koml.KOMLDeserializer");
        komlClassArgs = new Class[2];
        komlClassArgs[0] = java.io.InputStream.class;
        komlClassArgs[1] = Boolean.TYPE;
        komlArgs = new Object[2];
        komlArgs[0] = stream;
        komlArgs[1] = new Boolean(false);
        constructor = komlClass.getConstructor(komlClassArgs);
        koml = constructor.newInstance(komlArgs);
        readArgsClasses = new Class[0];
        methodRead = komlClass.getMethod("readObject", readArgsClasses);
        readArgs = new Object[0];
        closeArgsClasses = new Class[0];
        methodClose = komlClass.getMethod("close", closeArgsClasses);
        closeArgs = new Object[0];

        // execute it
        try {
            result = methodRead.invoke(koml, readArgs);
        } catch (Exception e) {
            result = null;
        } finally {
            methodClose.invoke(koml, closeArgs);
        }

        return result;
    }

    /**
     * writes the XML-serialized object to the given file
     * 
     * @param filename the file to serialize the object to
     * @param o        the object to write to the file
     * @return whether writing was successful or not
     * @throws Exception if something goes wrong while writing to the file
     */
    public static boolean write(String filename, Object o) throws Exception {
        return write(new FileOutputStream(filename), o);
    }

    /**
     * write the XML-serialized object to the given file
     * 
     * @param file the file to serialize the object to
     * @param o    the object to write to the file
     * @return whether writing was successful or not
     * @throws Exception if something goes wrong while writing to the file
     */
    public static boolean write(File file, Object o) throws Exception {
        return write(new FileOutputStream(file), o);
    }

    /**
     * writes the XML-serialized object to a stream
     * 
     * @param stream the stream to serialize the object to
     * @param o      the object to write to the stream
     * @return whether writing was successful or not
     * @throws Exception if something goes wrong while writing to the stream
     */
    public static boolean write(OutputStream stream, Object o) throws Exception {
        Class<?> komlClass;
        Class<?>[] komlClassArgs;
        Object[] komlArgs;
        java.lang.reflect.Constructor<?> constructor;
        Object koml;
        java.lang.reflect.Method methodAdd;
        java.lang.reflect.Method methodClose;
        Class<?>[] addArgsClasses;
        Class<?>[] closeArgsClasses;
        Object[] addArgs;
        Object[] closeArgs;
        boolean result;

        result = false;

        // get Deserializer
        komlClass = Class.forName("fr.dyade.koala.xml.koml.KOMLSerializer");
        komlClassArgs = new Class[2];
        komlClassArgs[0] = java.io.OutputStream.class;
        komlClassArgs[1] = Boolean.TYPE;
        komlArgs = new Object[2];
        komlArgs[0] = stream;
        komlArgs[1] = new Boolean(false);
        constructor = komlClass.getConstructor(komlClassArgs);
        koml = constructor.newInstance(komlArgs);
        addArgsClasses = new Class[1];
        addArgsClasses[0] = Object.class;
        methodAdd = komlClass.getMethod("addObject", addArgsClasses);
        addArgs = new Object[1];
        addArgs[0] = o;
        closeArgsClasses = new Class[0];
        methodClose = komlClass.getMethod("close", closeArgsClasses);
        closeArgs = new Object[0];

        // execute it
        try {
            methodAdd.invoke(koml, addArgs);
            result = true;
        } catch (Exception e) {
            result = false;
        } finally {
            methodClose.invoke(koml, closeArgs);
        }

        return result;
    }

}
